Many modern air-conditioners use inverter technology to control the speed of the compressor motor to drive a variable refrigerant flow. In this regard, traditional air-conditioners use a compressor which operates at a single speed and is switched on or off to control the temperature of the conditioned space. On the other hand, more modern air-conditioners use inverter technology having a variable frequency drive that controls the speed of the motor and thus the compressor and therefore the heating and cooling output of the air-conditioner.
Inverter technology has become common place due improved efficiency and smooth operation of air-conditioners with a reduction in costs of controlling electronics. However, because the compressor can now be operated over a wide range of frequencies, potential problems of noise and fatigue due to vibration may be exacerbated. While sources of vibration can be eliminated by damping or de-tuning equipment away from resonant frequencies with a compressor working at a constant speed, it can be difficult to identify all sources of vibration over a wide range of driving frequencies of the compressor of an inverter system. An analogous problem may occur with continuous control of fan speed, where a fan can be a source of vibration particularly in relation to annoying noises transmitted through cladding.
Vibration problems may be particularly difficult to overcome in situations where the mounting of the air-conditioner is in a wall or roof having relatively flexible construction. For example in a recreational vehicle, a roof mounted air conditioner can generate sympathetic resonant vibrations in the roof structure or other structural or cladding of the vehicle often located quite a distance from the air-conditioner. Noise from such vibrations can be particularly annoying to occupants and the resonant frequencies are beyond capability of prediction, occurring differently on a case-by-case basis depending on construction of the particular vehicle and its customization. Once an air-conditioner is installed, there may be little that the technician can do to solve the problem with prior art inverter air-conditioners.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.